Priority benefit under 35 U.S.C. xc2xa7119 or 35 U.S.C. xc2xa7365 is claimed to German Patent Application No. 198 56 627.1 filed Dec. 8, 1998 and Patent Cooperation Treaty Application No. PCT/EP99/09650 filed Dec. 8, 1999.
The present invention relates to a freewheel hub which is especially suitable for bicycles. However, this is not the only possible use; freewheel hubs of this kind may also be employed as drive for wheelchairs and other muscle-driven or non-muscle-driven vehicles and contrivances. For purposes of simplification, however, the invention will be described in the following with sole regard to its use with bicycles, whereby said description shall not in any way be deemed restrictive for the invention""s realm of application.
Freewheel hubs for bicycles are frequently realized with a ratchet freewheel in which rotatably mounted ratchet pawls are arranged between two rotating members and which effect a form-fit connection between these two members in one rotational direction and in the other rotational direction, the idle direction, move into a position in which no transmission of force can transpire between said rotating members.
The demands placed on such freewheel hubs are very high especially in the field of high performance sports, but not limited solely thereto.
On one hand, the freewheel hub must reliably take up intense forces; on the other hand, it must also function reliably, even over prolonged periods of time. Furthermore, the friction induced in the hub, in drive mode as well as in idle mode, must be as low as possible.
It is customary in the fields of professional and semi-professional cycling to service such hubs prior to every or almost every use. Therefore, it is also necessary that the hub be easily dismantled and reassembled.
It is therefore the task of the present invention to provide a freewheel hub especially for bicycles which withstands the most extreme loads, has low frictional values, provides reliable and sound operation, and which can be easily maintained.
This task is solved in accordance with the present invention by the object of claim 1, claim 17 or claim 18.
Preferred embodiments of the invention constitute the subject matter of the subclaims.
The present invention provides a bicycle hub with a high operational reliability and durability which is easy to maintain and which attains, upon transmission of force, a reliable, durable and form-fit connection combined with low frictional loss, for example even during a downhill ride when the pedal crank is in idle.
The hub according to the present invention comprises a hub axle, a hollow hub shell arranged concentrically thereto, a rotator arranged concentrically to said hub axle and on which at least one gear may be arranged, and a ratchet pawl freewheel means.
Roller bearings are utilized to support the individual components. The roller bodies of one or of all roller bearings are disposed at a predetermined distance from one another. Preferably standardized, respectively industrially fabricated, roller bearings are used according to, for example, DIN or ISO norms. The use of such roller bearings precludes the need for adjusting bearing play, a procedure which is costly and vulnerable to mistakes. In the bicycle industry such roller bearings are also known by the term xe2x80x9cindustrial bearingsxe2x80x9d as such bearings are usually industrially fabricated and are standardized.
Employing roller bearings or industrial bearings for bearing purposes has numerous advantages since the standard of quality of such industrially fabricated bearings is usually very high by virtue of the large number of pieces produced. A defective worn bearing can be simply and quickly replaced. The use of standardized bearings allows for acquiring high quality replacements quickly and at reasonable cost throughout virtually the entire world.
The rear wheel hub according to the present invention further comprises a freewheel means provided with ratchet pawls which is configured in such a way that rotator torque in the forward drive direction is transmitted to the hub shell, whereby the freewheel means is essentially configured radially so that upon a change in position of pawl, a frictional or form-fit connection is attained between the rotator and the hub shell.
The hub according to the present invention has numerous advantages.
The utilization of such roller bearings in which the roller bodies of a bearing are arranged at a predetermined distance to one another grants a high degree of reliability and durability to the inventive hub. It is specifically due to the individual roller bodies having a certain, usually fixed, spacing to one another that an inadvertent and frictional contact of the individual roller bodies can be avoided, a situation which can lead to increased wear and even deterioration of the roller bodies. With increasing wear, the outer contour of roller bodies may possibly deviate from their ideal, which can lead to cracking and waving of the races; this situation can conceivably destroy the entire hub.
Through the utilization of roller bearings preferably having an inner ring and an outer ring, between which balls, cylinders, cones or needles are usually retained in a bearing cage, an especially high degree of reliability and durability is achieved in the hub according to the present invention.
Industrially fabricated roller bearings ensure a high degree of quality and durability. Employing roller bearings having an inner ring and an outer ring has the result that a deterioration of a roller bearing does not usually lead to a progressive destruction of the hub, since the replacing of the complete roller bearing also encompasses replacing the inner and outer roller bearing race. In conventional bicycle hubs, a cone-shaped section on the hub axle often serves as the inner roller bearing race, while the outer race is formed in the hub shell. Upon deterioration of the roller bodies due to exceeding of their operating life or due to penetration of dust, the entire hub can thus be rendered unusable.
In a further preferred embodiment of the bicycle hub according to the present invention, the hub has a hollow hub axle which is so configured, in contrast to conventional hub axles, that the ratio, the difference respectively, between the outer and inner diameter is small, respectively the well thickness of the hollow hub axle is relatively thin, preferably between 0.5 and 3 mm and especially preferred between 1.7 and 2.3 mm; preferably at approximately 2 mm.
In a further preferred embodiment of the bicycle hub according to the present invention, at least two adjacently arranged roller bearings are utilized at one bearing position, instead of the just one roller bearing customarily utilized in conventional bicycle hubs. The utilization of two roller bearings at one position where normally only one roller bearing would be used has the advantage that the stress loaded on the individual bearing is smaller and thereby bearings of smaller outer diameter may be used compared to when only one bearing is used at this position. A reduction in bearing outer diameter leads to less material volume and, consequently, to a reduction in the total hub weight. This is of particular importance in sporting circles, but certainly not limited solely thereto.
The utilization of such a hollow hub axle or the use of two roller bearings at positions where normally only one roller bearing would be used is described in detail in the parallel application of the same applicant (attorney""s file No. 4582P197), which was filed with the German Patent Office on the same day as the present application and which describes a bicycle hub. The description, figures and entire contents of said application is consequently integrated herewith into the disclosure of the present application.
It is furthermore possible to mount one or several of the roller bearings utilized for bearing as floating bearings, in particular as axially floating bearings, whereby the fitting accuracy of said floating bearing is between 0.02 mm and 0.5 mm, preferably between 0.05 mm and 0.15 mm; particularly preferred at about 0.1 mm. When two adjacent roller bearings are utilized for bearing, it is especially preferred that one of the two be a floating bearing.
Preferably at least one bearing is a floating bearing on at least one side of the nub. Especially preferred is the most outward roller bearing relative the hub center being a floating bearing in order to avoid sustained tension in the bearing.
In a preferred embodiment of the bicycle hub according to the present invention, at least one of the prefabricated roller bearings has a seal for protection against dust and/or water. Preferably, the roller bearings for bearing the hub shell and the rotator with respect to the hub axle are provided with seals for protection against dust and/or water, and especially preferable is that all the roller bearings employed are provided with seals for protection against dust and water. Particularly preferred is the utilization of standardized, sealed roller bearings.
Preferably, roller bearings which are essentially maintenance-free are utilized. The use of maintenance-free and/or sealed roller bearings is especially advantageous since this increases the bearing operation life, making the hub more reliably sound for the cyclist.
In a preferred embodiment of the bicycle hub according to the present invention, one or respectively all of the roller bearings employed are grooved ball bearings which can be realized in accordance with a previous embodiment as maintenance-free or sealed grooved ball bearings. The utilization of grooved ball bearings is especially advantageous since these ball bearings can also take axial forces in addition to radial forces.
In a further preferred embodiment of the hub according to the present invention, in addition to grooved ball bearings, one or several needle bearings are also employed.
Preferably, grooved ball bearings are utilized for bearing the hub shell and the rotator with respect to the hub axle, while one or two grooved ball bearings or even one or two needle roller bearings may be utilized for bearing the rotator with respect to the hub shell.
Said bearing for supporting the rotator with respect to the hub shell may be provided with an inner ring and an outer ring, or with only one inner ring or one outer ring, or with only one ball retainer, a so-called needle ring respectively, in order to keep the overall structural height in radial direction as small as possible.
Especially when utilizing needle rings, but not limited solely thereto, it is possible to keep the radial space necessitated for the bearing small. This is especially advantageous since a smaller diameter of this bearing leads to smaller (material) volume and thus to overall less weight to the entire hub.
In a preferred embodiment of the bicycle hub according to the present invention, a freewheel carrier means is provided which is rigidly connected to the hub shell. The hub shell is made of metal, preferably a light metal and especially preferably, it is made from an aluminum alloy or a similar light metal. The freewheel carrier means is a separate component which is likewise preferably made from metal, light metal or an aluminum alloy; however particularly preferred is that it is made from hardened steel or similar material. The rotator is made of metal, preferably light metal, aluminum alloy respectively. In cases where especially high stress loads occurs, for example as in tandems, the rotator can also be made from steel, hardened steel respectively.
In a preferred embodiment, the freewheel carrier means is of essentially cylindrical shape and has a through borehole. At its end orientated to the hub shell, the freewheel carrier means has a polygonal outer cross-section profile in a cross-section perpendicular to the hub axle. The outer diameter of said freewheel carrier means at this end is dependent upon circumferential angle. The end of said freewheel carrier means as seen in axial direction may be of gear-like configuration, the sprockets or teeth of same being of pointed or round or sinusoidal shape. It is especially preferred that several, in particular 9, radial bulges are symmetrically distributed across the circumferential angle.
The hub shell is preferably provided with a polygonal shaped notch at a section of the rotator side perpendicular in cross-section to the hub axle which serves to essentially provide an interlocking form-fit reception of the polygonal shaped end of the freewheel carrier means. According to the design of the polygonal shaped end of the freewheel carrier means, the notch is such configured in the hub shell so as to enable a form-fit connection between said freewheel carrier means and said hub shell which is torque-proof and essentially free of play.
In a further preferred embodiment of the hub according to the present invention, a screw means is provided comprising a screw having a through borehole through its screwhead and screw shaft. A (male) thread is provided at least at the end of the screw shaft opposite the screwhead which can be screwed into a (female) thread of the freewheel carrier means at its end facing the hub center. The freewheel carrier means is mounted by inserting same into the hub shell. Due to the polygonal-like outer and inner profile of the freewheel carrier means and hub shell, a torque-proof and interlocking form-fit connection of freewheel carrier means and hub shell results. The screw of said screw means is introduced through the hollow center of the hub shell at its distal end from the freewheel carrier means, through a hub shell borehole corresponding to the screw shaft diameter, and screws into the freewheel carrier means. In the configuration according to the present invention, the screwhead positions against a stop in the hub shell so that a frictional connection in axial direction transpires between the freewheel carrier means and the hub shell.
The screwhead has notches or projections so that it can be turned by means of a tool.
In a further preferred embodiment of the hub according to the present invention, the freewheel means encompasses at least one ratchet pawl which is arranged on said freewheel carrier means and which engages into a groove or a corresponding tooth meshing on the inner peripheral surface of the rotator for the purpose of transmitting torque. Said rotator meshing is preferably configured such that in peripheral direction, the side of each tooth within the meshing ascends gradually, and then abruptly drops off at the top of said tooth.
Upon transmission of torque, the preferably two, three, four or more ratchet pawls of the freewheel carrier means engage in the rotator meshing and transfer the drive torque from the steep side of the gearing to the freewheel carrier means and then on to the hub shell. When the pedals are at a standstill, the pawls glide over the flat sides of the meshing and no torque is transmitted.
A number of recesses corresponding to at least one of said number of ratchet pawls which serve for receiving the paw is and which are preferably round or cylindrical in shape are preferably arranged in peripheral distribution at a central section of the freewheel carrier means.
Said ratchet pawls have an accordingly shaped end and are arranged in the corresponding recesses such that their second engaging ends can engage in the tooth meshing on the inner peripheral surface of the rotator.
The central section of the freewheel carrier means, on which the freewheel means is disposed, is preferably provided with a groove in peripheral direction in which an annular spring is arranged, and which stresses the freewheel elements or pawls such that the engaging ends of said pawls are raised in order to bring them into engagement with the rotator meshing. Said spring is preferably realized as a Q-spring and rings the freewheel carrier means at an angle of more than 360xc2x0. A small end section can be bent about 90xc2x0 at an end of the annular-shaped, Q-shaped spring respectively, said end section being then aligned essentially parallel to the axle in a determinate hub configuration and if necessary protruding as an axial bulge to the freewheel carrier means in order to fix same in peripheral direction. Employing a C-shaped spring is also possible.
Adjacent to this central section of the freewheel carrier means in the direction of the hub shell, a cylindrical section of larger diameter may be disposed on said freewheel carrier means on which at least one roller bearing is arranged for the purpose of rotatably supporting the rotator with respect to the freewheel carrier means and thus the hub shell.
It is preferred that a roller bearing is arranged essentially between the rotator and the hub shell near the rotator end distal the hub shell for the purpose of rotatably supporting the rotator with respect to the hub axle.
A bearing arrangement of this type, in which the rotator is rotatably supported on the one side of the freewheel means relative the hub shell and on the other side of the freewheel means relative the hub axle, is especially advantageous since it virtually excludes the rotator exhibiting pronounced bowing under load with respect to the hub shell, the freewheel carrier means respectively, even upon large burdens of torque as may arise, for example, during rides over mountainous terrain. Such bowing under load can invoke a single-sided stress on the freewheel elements, the ratchet pawls of the freewheel means respectively, which in turn subjects these components to highly increased wear.
Such a stable bearing essentially ensures that rotator torque will always be reliably transmitted to the hub shell. A rotator exhibiting heavy bowing under load relative the hub shell and/or the freewheel means may lead to, especially when cornering, the freewheel elements or the freewheel means ratchet pawls being unable to transmit torque to the hub shell.
Among the plurality of advantages of the hub according to the present invention is its reliable transmission of rotator torque in virtually all conceivable cycling circumstances.
In order to rotatably support the freewheel means relative the hub axle, a roller bearing is preferably arranged on the freewheel carrier means side distal the hub center.
In a preferred embodiment of the hub according to the present invention, the roller bearings for bearing the rotator relative the axle and for bearing the freewheel means relative the hub axle are arranged adjacently to one another and preferably separated only by means of a type of washer, a lock washer, or such similar component.
In a preferred embodiment of the hub according to the present invention, the hub may essentially be detached manually without the use of tools. Furthermore, the rotator as well is preferably able to be manually detached, removed respectively, without the need for tools.
In this preferred embodiment of the present invention, end retaining elements which are either screwed or simply just slipped onto the hub axle are provided on both ends of said hub axle.
Should said hub end retaining elements be screwed on, they preferably have a female threading while the hub axle end section has a male threading. A tool can then preferably be utilized for unscrewing said hub end retaining elements when dismantling the hub.
Should said hub end retaining elements be slipped on, they can be pulled off manually.
The further dismantling of the hub essentially always takes place without the need for tools. In all embodiments, the rotator is preferably manually extractable; consequently the interior enclosed by the rotator, for example the freewheel means, is accessible in a simple and easy manner when performing cleaning and maintenance duties. Especially advantageous hereby is that no roller bodies, for example balls or even ratchet pawls, can fall out of the hub after the rotator has been extracted.
In a preferred embodiment of the hub according to the present invention, a hub end retaining element in the form of a right adapter ring with a preferably V-shaped sealing means is slid onto the hub axle at the right-hand side of the hub shell on which the rotator is arranged, whereby an end, respectively a sealing wall of said V-shaped sealing means, is supported on a rotator dust shield gasket preferably situated adjacent the roller bearings for bearing the rotator on the hub axle.
On the left-hand side of said hub shell, a hub end retaining element in the form of a left adapter ring likewise With a preferably V-shaped sealing means is preferably slid onto the hub axle, An end of the V-shaped sealing means is supported on the hub shell and/or a roller bearing serving for the left-hand side bearing of said hub shell relative the hub axle for the purpose of preventing the penetration of dust and/or water into the hub interior.
It is furthermore preferred that an annular recess or groove is provided along the inner peripheral surface on the right inner side of said hub shell, the side an which the rotator is disposed, said recess or groove having a rounded-off shape in a cross-section parallel to the hub axle and configured such that the diameter on the right-hand end of said hub shell is smaller than the maximum diameter of said recess.
A sealing means is preferably disposed essentially between said rotator and said hub shell, which is preferably at least partially made of a flexible material and which fundamentally prevents the intrusion of dirt and/or water into the hub.
Said sealing means is preferably arranged on an outer surface of said rotator. Particularly preferred is said sealing means being disposed in a section of the annular recess of the hub shell and configured in such a way that an external pollutant load induces an increase in the sealing effect.
A configuration of this type is particularly advantageous in that the sealing effect intensifies upon increasing load, thus enabling an efficient sealing effect without an increase in frictional loss during standard operation.
In accordance with a further preferred embodiment of the inventive hub, the sealing means between the rotator and the hub shell is formed in a V-shape and situated so that the top of said V-shaped sealing means is orientated toward the hub center such that the V opens up outwardly.
Preferably a first sealing wall of the V-shaped seal situated between rotator and hub shell is positioned against the rotator, and the second sealing wall protrudes in to contact with the annular recess of the hub shell.
Such a configuration has numerous advantages, since the sealing effect of the seal is automatically increased upon being burdened by water splashed from outside, since the two sealing walls of the V-shaped seals, preferably at least partially made from flexible material, are pressed apart and the second sealing wall is then consequently pushed or pressed against the annular recess in the hub shell.
Hence, an intensified sealing effect of said sealing means is achieved while frictional losses are kept low during normal circumstances.
In a preferred embodiment of all the configurations as described previously, at least one of said sealing means comprises an additional labyrinth seal preferably connected in series to one of said flexible sealing means.
It is particularly preferred that an additional labyrinth seal is disposed in the sealing means between hub axle and hub shell on the left-hand side of the hub; an additional labyrinth seal can however also be arranged on the right-hand side of the hub in the sealing means of the hub axle relative the rotator and in the latter described sealing means above between rotator and hub shell.
The further embodiments of a hub according to the present invention includes characteristics such as described in the same applicant""s application No. DE 197 31 451.1, filed with the German Patent Office on Jul. 22, 1997 or No. DE 198 47 673.6, filed with the German Patent Office on Oct. 15, 1998. The contents of said applications are therefore integrated into the disclosure of the present application. The configuration of at least one or several sealing means, as is described in the same applicant""s DE 197 31 451.1 with reference to FIGS. 1, 2a and 2b, is especially preferred.